Automatic train stop



v 1m. RIGGLE.

AUTOMATIC TRAIN STOP. APPLICATION FILED SEPT. 4, 1920.

1,426,321. Q Q Pat nted Aug. 15, 1922.

4 SHEETS-SHEET I.

T. M. RIGGLE.

.AUTOMATIC TRAIN STOP.

APPLICATION FILED SEPT. 4. I920.

4 SHEETS-SHEET 2.

Patented Aug. 15, 1922.

M. RIGGLE.

AUTOMATIC TRAIN STOP. APPLICATION FILED SEPTA. I920.

- 1,426,321. Pat ntedAug.15, 1922.'

4 SHEETS-SHEET 4.

\- 7 (NI/E/VTOR.

rnom'ns' M.

nreenu, on OAKLAND, cenri oania, Assrenon or oNE-nren' ri-r To Linen. RIGGLE, on OAKLAND, canrroaivra- I AUTOMATIC TRAIN sror.

Specification'of Letters Patent. Patngnfigd kuog 15,

Application filed September 4, 1920. Serial No. 408,365.

To all who-m it may concern Be it known that I, Tnozu'n M, RIosLn, a citizen of the United States, residing at Oak'- land, in the county OfJ LlQJH'lQClZL and State of Cahforma, have invented a new and useful Improvement 1n an Automatic Train Stop, of which the following 1s a specification.

My invention relates to improvements in automatic train stops wherein a brake valve actuating mechanism adapted to set the air brakes on a train or the like, is arranged to be operated at regularintervals of distances traversed by-said train over a track comprising insulated sections of various lengths, and operates in conjunction with mechanism, or any standard block signalling system, to re set a retarding mechanism at a predetermined distance in advance of the farther end of an approaching insulated section provided A further object is to provide a deviceo't."

the characterdescribed wherein the train stop will be actuated should any portion thereof become broken or out of order, due to such defects asair leaks or broken electric circuitsin the various connections.

A still further object of the inventionis to provide improved meansfor actuating the standard brake valve now used on trains without interfering with the proper manipulatlon of said valve by the engineer or mo-v v torrnan, under normal conditions. i

A further ob ect of the lnventlon is to provide simple and improved means for resetting a retarding mechanism just previously to the entrance of a train into an insulated track section provided said section isclear" and-to prevent resetting of said retarding mechanism if said section is not clear.

A still further object oit'the. invention is to provide an improved device of the characterdescribed wherein l'flTg'H'O'VQQl means are provided to reset afretarding mechanism at a predetermined distance in advance of the farther end of an insulated section, whereby said retarding mechanism may be opermechanism just previously to the entrance of a train into the next adj acent section.

I accomplish these'and other objects by means of theimproved devicefdisclosed in the drawings forming a part of the present specification wherein likecharacters of reference are used to designate similar parts.

throughout'the said specification and. draw.- 1ngsj,and1nwh1ch: i

Fig: 1 1s a broken elevation of a portion of a locomotive tender and one of thetrucks thereofresting upon .a section of track and adjacent to a resettingjumper, or operating tachedthereto; Fig. 2is anenlarged broken elevation of thedeviceremoved from the truck; V Fig. 3 isva broken plan view'of Fig. 2; I

4 isan enlarged broken detail view of the automatic reversingmechanism whereby contact, disclosing my improved device at the retarding mechanism is moved forward when the'direction of movement of the train is reversed;

Fig. 5 is an enlarged transverse sectional view of a section of track disclosing the resetting contacts or jumpers, including a dia:

grammatic view of theengine cricuit oi the resetting mechanism;

F g. 6 1sacl1agraminatic view of several adjoining insulated track sections disclos-j ing the operation of the invention;

} Fig. 7 is a broken plan view of a standard brake valve disclosing' the 'brake'valve actuating mechanism applied thereto; a

M Fig. 8 is a broken detailed view of a portionoif the brake valveIdisclosingthe manner in -which the same isgenpgaged andfdis' engaged by the actuating mechanism theresetting valve and contacts; I y

' Referring to the drawings the numerall is used to designate a portion of a locomotive tender provided with the usual truckfa hav- 1 in wheels mounted upon standard axles Upon one end one' of the axles i Ihave mounted an extension 6 provided with a pinated to release the. brake valve actuating- Fig. 9 is end elevation of a portion 0t vFrgzEhand- I I s. Fig. 10 1s a broken detalle'd View of the re-,

clutch member 16 on the shaft 1%.

hereatter be termed, a resetting c,.

ion 8 which drives a gear 9 having a pinion 11 meshing with the gear 12 which in turn rotates a shaft 14 upon which is slidably mounted or feathered a double ended clutch member 16 arranged to engage either one of a pair of clutch members 17 and 18 connected to oppositely faced or positioned bevel gears 19 and 20, respectively, loosely mounted upon the shaft l t. The bevel gears 19 and 20 are constantly in mesh with a third bevel gear 22 rotatably mounted within a suitable bearing 23 and connected to a beveled pinion 24 which in turn meshes with and rotates a beveled gear 26 having. a knurled edge, the purpose of which will hereinafter be more fully described.

Rotation of the axle in a clockwise direction, assuming that the train is moving forward and toward the right, will, through the train ofgears above described, rotate the beveled gear 26 clockwise as indicated by the curved arrows in Fig. 1 of the drawings. Also connected to and rotating with the axle 4 is a bevel pinion 28 meshing with and a bevel ear 29 connected'to a disc- 31 provided with a plurality of flat conveired pins 32 arranged at regular intervals annularly on one "face of said disc 81 and adjacent the periphery thereof, said pins fjzengagin q the flexible end 33 of a lever 34L operatively connected to the double ended Rotation of the disc 31 will cause the pins 32 there on to engage said lieirible end 33 and thereby retain the double ended clutch member 15 in eigaging relation, with either one of the clutch members 17 and 18 of the bevel gears, 19 and 20, respectively, disclosed in of the drawings, the urpose of which novel arrangement will her inafter be more fully set forth.

Pivotally mounted upon the shaft 36 of. the bevel gear 26 is an arm 37 extending slightly beyond the periphery of said ear 26 and having oivotally mounted thereon an eccentric cam arranged. to engage the l-znurled periphery of said gear 26 when said cam 38 is moved in one direction, and to release said periphery when moved in the opposite direction.

A link 39 pivotally connects an extension 4:1 of the camBS to a piston stem -12 having large and small. pistons 43 and 44 mounted upon opposite ends thereof and shdably mounted within large and small cylinders 46 and 47 respectively. the said cylinder 47 having a V-shaped slot out in-the open end thereof, the purpose of which will hereinafter he more fully described.

The hereinbefore mechanism may be set within a suitable housing or box ll) for protective purposes.

A pipe connection 51 connectsthe cylinder 4&6. which for purposes of llustration. shall d er with the main reservoir, not shown, of any standard air brake system.

The pipe [.31 is provided with a valve 52 which is .nori'nall held closed by a spring attachec to an armh l of the valve 52, said arm 5% being pivotally connected to and operated by a solenoid 56.

The cylinder 4:7, which shall hereafter be termed a releasing cylinder, is connected by m ans of a pipe 58 to a brake Valve actuat )Q cylinder 3%? which in turn is connected to tneapplication pine 6? of the air brake system hereinhefore referred to.

Slidablv mounted within the actuating $35) is a piston the stem 63 of vwhich has its outer end slidably mounted upon a standard brskevalve indicated in general by the numeral 64;, disclosed in l i g. 7 of the drawings. The stem, is nrovided with a pivotaliv mounted and sprint? controlled pawl 66 having depending arcuate flange 6'? thereon to engage a lug68 on an extension '89 ot the bralre valve conlevcr ii. The fit-11 I when moved toward the left is p e the lug 68 of the lever 71., when in running position, and move the same to service position when the piston 62 is actuand to release said lug is moved toward the r -v L- 1 V .1 words, the operating lever '11 or the brake,

valve 64; is free to be moved at all to any position times. and is o "ed'by tie pawl and mor to service 110st tion when the automatic train stop is operated. i

' connection 73 leads lrom the main pe, not shown, of the standard air brane system to the actuating c linder 59 and. on the opposite side of the piston 62 therein from the application pipe The pipe connection 73 is provided with a thrc way cock 74!; arranged to normally permit the passage of air under pressure to the actuating cylinoer 59, when in one position and to prev lit the passage of air to said cvlinder d o 'ief'the same to the atmosphere when; in theoppositeposition.

The valve 74-. is nor nally held in the first mentioned positionhv means of a suitable spring 75 connected tothe operating lever 76 of said valve 74., and said lever 76 carries an armi"? adapted to close an electric switch 78 when moved to opcn'the actuatin cylinder 59 to the atmosphere, the purpose forth.

68 when said 1 J 67 of the pawl 66, arranged to.-

A contact shoe 81 is mounted upon a bar 82 of any suitable insulating material on each side of the train. which bar has its ends slidahly mounted within slotted cylinders 83 dependin. ,1 cm the t uss rods 01- struts of the trnci; and suitable springs 84 are interposed between the said Ends and the upper .(ls of said cylinders 83 whereby cable 91 leads from the other side of said battery 89 to the solenoid 56 hereinbefore described and from thence a cable 92 leads to the other contact shoe 81 on the opposite side of the train.

The switch 7 8 hereinbetore described and disclosed inFigs. 7 and 10 of the drawings is connected in series with the battery 89 and solenoid 56 by means of suitable wires or connections 93 whereby the solenoid 56 may be operated independently of the automatic train stop if required.

The track, comprising the two parallel rails 87, is divided into insulated sections as at present in common use with standard block-signalling systems, and the present invention may be used in conjunction with said standard systems all of which are substantially the same in this respect, viz; a battery 94 has the opposite sides thereof connected to opposite rails 87 of each section, while at another portionot said section an electro-magnet 96 or what is commonly known as a track relay, is connected in series with the rails 87 and battery 94. The track relay being energized, when that track section is clear, an armature 97 is attracted to close contact, by means of a member 98, between a pair of terminals 99 of wires 190 connected to the track contacts 86. The track sections and electrical connections pertaining to each track section will hereinafter be designated as blocks to differentiate the same from said track sections.

For purposes of illustration the wires 100, contacts 99, member 98 and track shoes 86 will herein be termed a jumper as it serves to carry or jump current from one contact trip 81 to the other.

If any of the wires or connections in the circuit of any block should become disconnected, broken or otherwise inoperative, or if the block circuit through the rails 87 oi any section become shorted by the presence of a train or other pair of wheels in that section, the current from the track battery 94 will be shorted and the-track relay 96 will be tie-energized and the member 98 will drop, being actuated by gravity, to break the connection between the contacts 99 and therefore no current can pass from the battery 89 in the train to energize the solenoid 56.

The operation of the automatic train stop is as follows:

While the train is in motion the operating lever 71 of the brake valve 64 will be positioned in the running position and the pawl 66 on the stem 68 will lie slightly beyond the lug 68 of the extension 69 of the said operatinglever 71, as disclosed in Fig. 7 of the drawings.

The pawl 66is held in this position by the pressure of air in the. application pipe 58 or 61 side of thepiston 62 in the actuating cylinder 59 for the reason that pressure in said pipe is greater than the pressure in the opposite or main brake pipe 73 side of the piston 62. While in this position the pawl 66 will readily permit the passage of the lug 68 so that the brake valve 64 may be. operated in the usual vmanner for controlling the train without interference by the pawl 66! The pipe 58 is connected to the releasing cylinder 47 and the pressure thereby provided therein tends to mov the piston 44, piston stem 42 and piston 43 on the opposite end of said stem in the direction indicated in Fig. l of-the drawings. Compression of air in the cylinder 46 by inward movement of the piston 43 will be prevented by the rovision of a bleeding hole 40.

As the piston stem or rod 42 moves toward the right under pressure of the air within the cylinder 47 the link 39 actuates the cocentric cam 38 to engage and bind upon the knurled periphery ofthe large bevel gear 26 but as said gear 26 is directly connected to the aXle 4 of the tender 1 it is evident that the train of gears hereinbefore described'will operate as a retarding means to retard movement of the piston 44 within the releasing cylinder 47. As the piston rod or stem 42 is thus directly connected to the wheels 3 of the tender it is obviousthat movement of said piston rod will be in direct proportion to th distance traveled, regardless of the speed or revolutions per minute of said 'wheels 3. Therefore assuming that the piston 44 is moved to its extreme 'inward'limit it is evident that thesaid piston cannot be moved outwardly while the tender isnot in motion but can be moved outwardly While" the tender is in motion but such outwardmovement will be in direct proportion to the distance, and not the speed, traveled by said tender 1. In other words, assuming the train to be continually in motion and the piston 44 starting from its extreme inward position within the releasing cylinder 47, 1

said piston 44 will be moved to uncover the \l-shaped aperture or recess 48 when a pre determined distance has been traversed by said train which distance, for convenience of illustration, Ihave assumed to be a quarter of a mile. I v

lVhenthe piston 44 of the releasing cylinder 47 is moved outwardly a distance suiticient to uncover the V-shaped aperture. 48 air is permitted to escape through said aper ture 48 which will reduce the pressure within the pipe 58 and also in the brake valve actuating cylinder 59, in Fig. 7 of the drawings, until the pressure on the opposite side of the piston 62 in said cylinder 59 is greater and sufficient to move the piston 62 to actuate th pawl 66 which then moves inwardly and in so doing engages the lug 68 on the extension 69 of the operating lever 71 of the brake e 61 and moves said lever 71 to service position as indicated in dotted lines in Fig. 7 of the drawings.

Movement of said operating lever said service position will actuate the brake valve 64- and other portions of the air brake system, not shown, and bring the train to a stop. When the piston rod or stem 63 has been actuated to move the operating lever 71 to service position, the pawl 66 and its depending arcuate portion 67 will be moved to a position where the lug 68 may freely pass through the ap 65, disclosed in Fig. 9 of the drawings, at the upper end of the arcuate flange 67. In this manner a valve actuating mechanism is provided that is adapted to move the operating lever from running to service position without other wise interfering with the operating of said lever 71 by the engineer or motorman.

Referring to Fig. 6 of the drawings we will assume that the train is positioned at A and running in the direction indicated by the arrow. The track is divided into unequal insulated sections. Movement of the train will rotate the gear 26 and permit outward movement of the piston 4a in the releasing cylinder 4-7. But, previously to arrival of the piston 4st to the V-shaped recess 48 in said cylinder 47 the contact shoes 81 contact with the track trips 86 or the next block, and as said block and its associated track section is clear and the circuit thereof in proper working order the track relay 96 is energized and the contacts 99 closed and therefore current from the engine battery 89 will flow through the solenoid 56, open the valve 52 in the main reservoir pipe 51 and permit air under pressure to enter the larger resetting cylinder l6 and thereby move the linl: 39 to release the. cam 38 from the knurled periphery of the gear 26 and move the arm 37 and piston l t in the releasing cylinder at"? to the beginning of the operative position, the cross section of piston 43 being larger than that of piston 44:, thereby resetting the retarding mechanism and preventing operating of the actuating cylinder 59. As the succeeding section just described is illustrated as a shorter section it should be noted that the track trips 86 are situated considerably in advance of the entrance to said section. The purpose of this arrangement is to provide that the resetting operation shall occur at a predetermined distance in advance ot the farther end of the section, regardless of the length of said section. The piston 44,

influenced by the resetting mechanism, moves from its extreme reset position to its "full operating position while the train moves a regular and predetermined distance, regardless of time or speed. Thus, it appears that the electrical connections for each section of track, or blocks as l have designated them, are 01": a regular predetermined length which is not dependent upon the length of the track section with which it is associated. Thus, the trips 86 being placed a definite distance in advance or the farther end o1 the track section, may fall at any point within said section or the preceding section, or in case of a number or extremely short track sections, the blocks might extend over several traclr sections.

It is not necessary that the piston be advanced to its exereme position before resetting as the resetting operation may occur at any intermediate point. Thus in traversing a. short section the piston 4% may have advanced only a small portion or its course when reset for the succeeding section, such resetting being arranged to cause the auto 'matic operation of the br l; at or near the end oi said succeeding section should the fol-- lowing section be blocked.

It is thus seen that the tract: trips 86 are always at the same distance from the farther end of the section being approached regar less of the length or the section or the adjacent sections, provided only that such sections do not exceed the resetting dis ance.

in Big. 6 or the drawings I have illustrated an obstruction B in a section being approached, which obstruction may be in the form oi any set of wheels 3 connected on an axle ft to bridge the rails 87 and thereby short circuit the current from the track battery 94-. The traclr relay 96 of the block cor responding to that section will therefore be de-energized and the continuity of that section jumper will be broken.

The diagram in heavy lines in Fig. 6 of the drawings illustrates the resetting operation of the train stop so that the train may travel to the far her end of the section being approached meantime passing the advanced track trips of the closed or block section.

the said contacts are not electrically connected the resetting operation will not take place and the piston a l will uncover the recess or aperture 4.8 in the releasing cylinder 4-.7 before said blocked or closed section is reached and the train will be stopped by the automatic action of said stop mechanism before entering the closed block or section.

From the foregoing it is obvious that the releasing cylinder will be reset at a predelOO termincd distance in advance of the farther operation will be omitted if the said section is not clear the train automatically stopped before entering said block.

It is obvious that the gear 26 must rotate in the same direction regardless of the direction of movement of the train. 7 To automatically provide for this one way rotation of the gear 26 I have provided the automatic reversing gear which operates as follows:

As long as the train moves forward the beveled gear 28 attached to the end of the axle a will rotate the bevel gear 29 and disc 31 attached thereto in a direction which will cause the pins 32 to engage the flexible end 33 of the lever 34 and retain the double ended clutch 16 on the shaft 14: in engaging relation with the bevel gear 20 to rotate the gear 26 in a clock-wise direction.

When the direction of movement of the train is reversed the pinion 28 rotates in the opposite direction and thereby reverses the direction of rotation of the disc 31 and pins 32 thereon. This reversal ofthe direction of rotation of the disc 31 will cause one of the pins thereon toengage the flexible end 33 of the lever 34 and move the double ended clutch member 16 into engagement with the bevel gear 19 thereby continuing the rotation of the bevel gear or pinion 22 in the same direction for the reason that the bevel gear 19, now being driven by the shaft 14, is in contact with the opposite side of the gear 22 from the bevel gear 20 and the shaft let is rotating in an opposite direction.

hen the train is again moved in a forward direction the pins 32 will again operate the clutch member 16 to move the gear 26 forward. I 7

When the automatic stop has actuated the actuating piston 62 and the train has been brought to a stop the device may again be reset by operating the three-way valve lever 76 against the tension of the spring 7 5 connected thereto until the interior of the actuating cylinder 59 on the mainbrake pipe side 01" the said cylinder 59 is opened to the atmosp iere and said train pipe 73 is closed. Simultaneously the arm 77 attached to said lever 76 closes the switch contacts 78 in series with the engine battery 89 and solenoid 56 and thereby opens the, valve 52 of the main reservoir pipe 51 and the device is reset. 1

As the main brake pipe side of the actuating cylinder 59 is opened to the atmosphere through the three-way cook or valve 74 it is evident that the pressure on the opposite side of the piston 62 in said cylinder 59 will move said piston 62 and the pawl 66 pivotally connected thereto to operative position. During such movement. of the piston 62 and its stem or rod 63, the spring controlled pawl 66 will be depressed toward said stem or rod 63 while passing it the section of track being approached not clear. It is also obvious that thesections may be of irregular length and that the device will be controlled to stop the train at the end of a clear section regardless of the length of saidsection, provided the next section is blocked. It is also evident that the device will be operated and controlled regardless of the. directionof movement oi"- the train, and also, that while actuating the brake valve that said brake.

valve always remains unobstructed and may be manipulated by the engineer or motorrnan without interference w 1 t h the automatic sto I laving thus described my invention what I claim as new and desire to secure by Letters Patent is: v

1. An automatic train stop comprising an actuating means for engaging and actuating the brake valve of a standard a1r brake systemto stop a train; controlling means for controlling the actuating means for actuating the valve; and retarding means actuated by movement of said train for retarding the actionof the controlling means whereby said controlling means may be operated at the ends of predetermined distances travelled by the train. I I

2.-An automatic train stop comprising an actuating means for engaging and actuating a brake valve of a standard a1r brake system to stop a train; controlling means for controlling the actuating means to actuate said brake valve; retarding means actuated by movement of said train for retarding the action of the controlling means through regular periods whereby said means may be operated at the ends of predetermined distances trav elled by the train; and means for resetting the retarding means previously to reaching to the ends of said distances when a predetermined section of a track being approached by said train is unobstructed.

3. An automatic train stop comprising an actuating means arranged to engage and move a brake valve of a standard air brake system from running to service position; controlling means for controlling the actuating means to actuate said brake valve; retarding means actuated by movement of a train for retarding the action of the controlling means through regular intervals of distance traveled by said train and to permit operation of said controlling and retarding means at the end of said periods; and means for resetting said retarding means, to prevent operation of said controlling and actuat ing means, just previously to the end of each regular interval When a predetermined sec-- tion of track being approached by said train is unobstructed.

4i. An autom tic train stop comprising an actuating me ns arranged to engage and move a bralte valve of a standard air brake system from running to service position; controlling means for controlling the actuating means to actuate said brake valve; retarding means actuated by movement of a train for retarding the action of the controlling means through regular in tervals of distance traveled by said train and to 1 mit operation or said controlling andretarding means at the end of said periods; and means fo resetting said retarding means, to prevent operation of said controlling and actuating means, just previously to the end of each regular interval when a predetermined section of track being approached by said train is unobstructed; and means for operating the retarding means in the same direction when the direction of movement oi": the train is reversed.

5. An automatic train stop comprising an actuating means arranged to engage and move a brake valve of a standard air brake system from running to service'position; controlling means for controlling the actuating means to actuate said brake valve; retarding means actuated by. movement of a train for retarding the action of the controlling means through regular intervals of distance traveled by said train and to permit operation of said controlling and retarding means at the end of said periods; and means stop a train; controlling means for control ling the actuating means to actuate the brake valve and stop the train; means actuated by the movement of a train in either direction for retarding the operation of said controlling means and-for permitting such operation at the end of regular intervals of distance traversed by said train; and means for resetting the controlling means just previously to said controlling operation. to prevent the same when an interval of track being ap proached by said train is clear.

7. An automatic train stop comprising an actuating means arranged to engage and move a brake valve of a standard air brake system from running to serviceposition to stop a train; controlling means for controlling the actuating means to actuate the brake valve and stop the train; means actuated by the movement of a train in either direction for retarding the operation of said controlling means and for permitting such operation the end of regular intervals of distance traversed by said train; and means for resetting the controlling means just previously to said controlling operation to prevent the same when an interval Oili track be; ing approached by said train is clear; and for preventing operation of said resetting means when said interval is obstructed.

8. The combination with a track comprising insulated sections, of actuating means for eng ging and actuating abralre valve of a standard brake system to move the same from running to service position; controlling means ior controlling the actuating means to permit operation of the same at regular intervals of distance traversed by a train on said track sections; retarding means actuated by the movement of said train to retard the action of the controlling means until near the end of an interval; resetting means arranged to reset the controlling means; and means actuated by an unobstructed track section being approached by said train for operating, the resetting means just previously to the entrance of said train on said section.

9. The combination With a series of insulated track section of various lengths, of actuating means arranged to engage and actuate a brake valve of a standard air brake system of a train to move said valve from running to service position to stop said train; controlling means arranged to control said actuating means to actuate said valve; retarding means actuated by movement of said train and arranged to retard the action of the controlling means through regular intervals of distance and to permit operation of said controlling means at the end of said interval; and resetting means arranged to be actuated by an unobstructed section being approached by the train for resetting the controlling and retarding mechanism at regular and predetermined distances in ad vance of the farther end of a track section being appr ached by said train.

10. In an automatic train stop, the combination of a a series of insulated track sections; trips positioned a predetermined distance from the ends of said sections; brake valve actuating mechanism arranged to engage and actuate the brake valve of a train from running to service position controlling 1 means for controlling the actuating mechanism to actuate the brake valve; retarding means actuated by movement of a train in either direction to retard the action of said control means through regular intervals of distance traversed by said train; and re* a setting means actuated by said air brake system and said trips to reset the controlling and retarding means in advance of an unobstructed track section being approached and a predetermined distance in advance of the farther end. of said section.

11. In an automatic train stop, the combination of a series of insulated track sections; trips positioned a predetermined distance from the ends of said sections; brake valve actuating mechanism arranged to engage and actuate the brake valve of a train from running to service position; controlling means for controlling the actuating mechanism to actuate the brake valve; retarding means actuated by movement of a train in either direction to retard the action of said controlling means through regular intervals of distance traversed by said train; and resetting means actuated by said air brake system and said trips to reset the controlling and retarding means in advance of an unobstructed track section being approached and a predetermined distance in advance of the farther end of said section; and means for resetting the controlling and retarding} means independently of the trips.

12. An automatic train stop comprising an actuating means arranged to engage and actuate a brake valve of a train having a standard air brake system to stop said train; controlling means for controlling the actuating means at regular intervals of distance traveled by said train; retarding means actuated in operative direction by forward movement of said train to retard the action of the controlling means through said regular intervals of distance; means for resetting the controlling and retarding means previously to the end of an interval when a predetermined section of track being! 'ap proached is unobstructed; and means for automatically retaining movement of the retarding means in the operative direction When the direction of said train is reversed.

In Witness whereof I hereunto set my signature. 

